If some of the codes work while others don't then checking to see if your PS2 Game Version is the first version will help greatly answer a few questions!
You see all or most of the codes that are created are made for the first version, if yours is a greatest hits or part of a collection then they tend to be a different version. That means that the makers made some changes to to, and the address that the code points to is not the correct address. In most cases this can be the reason why the codes does not work. You can also have a different version that we call a bug fix (also known as patched), this is where the makers made a change to it to fix problems found after the first release. One of the ways we can tell if yours is a different version is by posting the PS2 Game Serial Number. All games have this. It is really hard to read and is located somewhere on the ring! Some will start with PDSS others may start with SLUS.
Another thing to try is if the codes was not preloaded (meaning that the codes did not come with the disk) then it could mean that you made an input error when you manually entered the code. Check ALL the digits will help solve this. It only takes 1 digit to be wrong for a code to not work!
FYI: Other cheat devices means just that. Not made by MadCatz Inc.
ALSO Please avoid double, triple posting (this is where you don't wait for someone else to post before your next post). Please make use of the Edit button, it looks something like this:

Clicking on that allows you the user to edit your post. This includes adding things to it or removing things to it!
I have merged your 2 posts you made into one! Please don't let it happen again!